<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      let year = prompt("请输入年份");
      if (year % 4 == 0 && year % 100 != 0 || year %400==0) {
          alert("是闰年");
      }else{
        alert("是平年");
      }
    </script>
  </body>
</html>
